In a condition of meeting the optical performance requirements of an optical system, using a spherical surface or an aspheric surface to replace a freeform surface of the optical system can reduce a cost and a difficulty of processing and testing. A hybrid surface optical system comprises different surfaces. Each surface of the hybrid surface optical system can be selected from spherical surface, aspheric surface, and freeform surfaces. Thus, compared to freeform surface optical systems, the hybrid surface optical system has low cost and small processing and testing difficulty.
However, conventional off-axis hybrid surface three-mirror optical system are mainly applied to linear field of view with small field angles and large F-number, but the applications in the field of view with large field angles and small F-number are limited.